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                                                                       Exhibit 5

                    Venable, Baetjer, Howard & Civiletti, LLP
                            1201 New York Avenue, NW
                                   Suite 1000
                              Washington, DC 20005
                                 (202) 962-4800


                                  August 13, 2001

Celsion Corporation
10220-I Old Columbia Road
Columbia, Maryland 21046

        Re:    Registration Statement on Form S-8

Ladies and Gentlemen:

        We have acted as counsel to Celsion Corporation, a Delaware corporation
(the "Registrant"), in connection with a registration statement on Form S-8 of
the Registrant (the "Registration Statement") filed this day with the Securities
and Exchange Commission (the "Commission") pursuant to the Securities Act of
1933, as amended (the "Securities Act"), pertaining to the registration of ten
million (10,000,000) shares of the common stock, par value one cent ($0.01) per
share, of the Registrant (the "Shares") for issuance and sale pursuant to the
Celsion Corporation 2001 Stock Option Plan (the "Plan").

        This opinion is being furnished in accordance with the requirements of
Item 601(b)(5) of Regulation S-K under the Securities Act.

        In connection with this opinion, we have considered such questions of
law as we have deemed necessary as a basis for the opinions set forth below, and
we have examined or otherwise are familiar with originals or copies, certified
or otherwise identified to our satisfaction, of the following: (i) the
Registration Statement; (ii) the Certificate of Incorporation and Bylaws, as
amended, of the Registrant, as currently in effect, certified by the Secretary
of the Registrant; (iii) certain resolutions of the Board of Directors of the
Registrant relating to the adoption of the Plan and the issuance of the Shares
and the other transactions contemplated by the Registration Statement, certified
by the Secretary of the Registrant; (iv) the Plan; and (v) such other documents
as we have deemed necessary or appropriate as a basis for the opinion set forth
below. In our examination, we have assumed the genuineness of all signatures,
the authenticity of all documents submitted to us as originals, the conformity
to original documents of all documents submitted to us as certified or
photostatic copies and the authenticity of the originals of such copies. As to
any facts material to this opinion that we did not independently establish or
verify, we have relied upon statements and representations of officers and other
representatives of the Registrant and others.

        We have also assumed that the Registrant shall have sufficient
authorized and unissued shares of Common Stock available at the time of each
issuance of Shares and that the relevant

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Celsion Corporation
August 13, 2001
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provisions of the Certificate of Incorporation and Bylaws of the Registrant and
the Delaware General Corporation Law in effect at the time of issuance of any of
the Shares will not differ in any relevant respect from the analogous provisions
of the Certificate of Incorporation and Bylaws of the Company and the Delaware
General Corporation Law in effect as of the date of this opinion and that no
additional relevant provisions shall have been added subsequent to the date
hereof.

        Based upon and subject to the foregoing, we are of the opinion that the
Shares have been duly authorized for issuance and that when issued, sold, paid
for and delivered in accordance with the terms of the Plan, the Shares will be
validly issued, fully paid and nonassessable.

        This letter expresses our opinion with respect to the Delaware General
Corporation Law (without regard to the principles of conflict of laws thereof)
as in effect as of the date hereof. It does not extend to the securities or
"blue sky" laws of any jurisdiction, to federal securities laws or to any other
laws and we do not express any opinion as to the effect of any other laws on the
opinions stated herein. We assume no obligation to update the opinions set forth
herein.

        We hereby consent to the filing of this opinion with the Commission as
an exhibit to the Registration Statement. We also consent to the reference to
our firm under the caption "Legal Matters" in the prospectus that forms a part
of the Registration Statement. In giving such consent, we do not thereby admit
that we are included in the category of persons whose consent is required under
Section 7 of the Securities Act or the rules and regulations of the Commission.

                                 Very truly yours,

                                 /s/ Venable, Baetjer, Howard, & Civiletti, LLP